Cs₄PMo₁₁VO₄₀-Catalyzed Glycerol Ketalization to Produce Solketal: An Efficient Bioadditives Synthesis Method

In this work, a series of vanadium-substituted phosphomolybdic acids were synthesized and tested as the catalysts for the synthesis of solketal, a green fuel bioadditive, from the condensation reaction of glycerol with acetone. The objective was to demonstrate that an easily synthesizable solid catalyst can efficiently promote glycerol condensation with acetone at room temperature. The activity of pristine heteropolyacid (i.e., H3PMo12O40) and its vanadium-substituted cesium salts (Cs3+nPMo12-nVnO40; n = 0-3) was evaluated in condensation reactions carried out at room temperature. Among the catalysts tested, Cs4PMo11VO40 was the most active and selective towards a five-member ring solketal isomer (dioxolane). A high yield of solketal (i.e., 95% conversion and 95% selectivity to solketal) was achieved in glycerol condensation with acetone at room temperature within a short reaction time (2 h). The influence of the main reaction parameters, such as the acetone-glycerol molar ratio, catalyst load, and reaction temperatures, was investigated. The greatest activity of the Cs4PMo11VO40 catalyst was correlated to its greatest acidity.